Results
Of 17 countries, 12 (70%) reported testing influenza surveillance specimens for more than half of the weeks during May 1 – December 31, 2020 (Table 1). These 12 countries tested 17,407 surveillance specimens, with 592 (3.4%) testing positive for influenza viruses. Influenza A(H3N2) viruses were detected in 573/592 (97%) influenza positive specimens. From April 27-July 26, 2020 (epidemiologic weeks 18-30), specimens tested decreased from an average of 14,102 per year in 2015-2019 to 3,969 (71.9% decrease) and influenza positivity from 22% to < 1%. During weeks 31-53, specimens tested decreased from an average of 24,782 per year in 2015-2019 to 13,438 (45.8% decrease) and influenza positivity from 18% to 4%.
Of these 12 countries, six (Bangladesh, Kingdom of Cambodia, Lao PDR, New Caledonia, Singapore, and Viet Nam) maintained testing of surveillance specimens for >90% of weeks. In these countries we observed considerable variability in influenza circulation. In each of these six countries, influenza circulation was unseasonably low, or absent, during weeks 18-30, 2020. However, during weeks 31-53, the percentage of surveillance specimens testing positive for influenza approached or reached positivity rates of 2015-2019 in Bangladesh and Cambodia; and increased but remained lower than historical positivity in Lao PDR and Viet Nam. No influenza viruses were reported by New Caledonia and Singapore.